In recent years, ocean current power generation devices that generate power using seawater flows such as ocean currents (i.e., tidal currents) and the like have been developed.
The device described in Patent document 1 is one example of this type of ocean current power generation device that generates power using the flow of seawater. This ocean current power generation device is a twin-motor underwater floating-type power generation device in which a pair of power generation units that each have a horizontal axis-type turbine that is rotated by ocean currents are connected together in parallel with each other by a connecting beam.
In this ocean current power generation device, variable pitch turbine blades are employed in each turbine of the pair of power generation units. By using variable pitch turbine blades for each turbine blade, it is possible to adjust the pitch such that the flow resistance and output of each turbine does not exceed a predetermined value.
Moreover, in this ocean current power generation device, the pair of power generation units that are linked together by a connecting beam are tethered to the seabed via a buoyancy-imparting supporting strut that is used for depth control and via three tether cables. By controlling the length of at least one tether cable out of the three tether cables that connect the buoyancy-imparting strut to the seabed by means of a length control unit that is provided on the buoyancy-imparting strut, the depth and posture of the pair of power generation units are controlled.